The present invention is directed to the field of mold design. More particularly, the present invention is directed for providing undercut release for molding parts having undercuts. Internal core lifters are used within a mold device to mold and eject undercuts in injection molds. An internal core lifter generally consists of a core blade seated at a predetermined angle achieved by mounting one end of the core blade at a fixed angle to a coupling which then slides linearly along a support mounted to the mold ejection plates.
In order to mold undercuts and eject the parts, the core lifter has a core blade that is attached to one ejector system of the mold, and the opposite end of the core blade is used to mold and eject the part. To mold undercuts, the core blade is placed at an angle determined by the mold design. Since one end of the core blade is configured to mold the undercut of the plastic part, the core blade is required to move horizontally away from the undercut during a vertical ejection of the part. This horizontal movement is necessary during ejection so as not to damage the part.
In a typical prior art undercut release system, an ejector blade is engaged with the mold. The ejector blade travels through a slide or slot in the mold. One end of the ejector is configured to provide the undercut of the molded part when the ejector blade is aligned with the internal mold cavity of the mold. The opposite end of the ejector blade is attached via a coupling to an ejector plate. The coupling is designed to transmit pushing and pulling forces to the ejector blade. The coupling is also designed to allow the ejector blade to travel in a linear direction to provide clearance for the formed undercut of the part. The movement of the ejector blade forward provides clearance from the undercut and the movement of the ejector blade upward helps eject the part from the mold cavity. A representative example of such a prior art undercut release system is disclosed in U.S. Pat. No. 5,137,442.
Previous undercut release apparatuses have relied on planar motion of the core lifters to provide release from the molded undercut. However, due to the part configuration, it may be desirable or necessary for the release mechanism to travel off plane in order to avoid damaging the molded part. Such off plane, or three-axis, movement is a hallmark of the present invention.
In one embodiment, the invention comprises an apparatus for molding parts having at least one undercut, the apparatus comprising: (i) an undercut release component having a body with a first end configured for molding a part having an undercut wherein the undercut release component is capable of movement whereby the first end moves away from the undercut in a 3-axis path.
In another embodiment, the invention comprises an undercut release component comprising: (i) a body having a first end configured for molding a part having an undercut and an opposite second end adapted for transmitting and receiving both pushing and pulling forces, wherein the undercut release component is slideably engaged with an injection. mold assembly; and, (ii) a coupling engaged with the second end for transmitting pushing and pulling forces to the second end and allowing nonlinear movement of the second end, wherein the undercut release component is capable of movement whereby the first end moves away from the undercut in a 3-axis path.
In-another embodiment, the invention comprises a process for providing undercut release in a mold, the process comprising the steps of: (i) providing an undercut release component having a first end, the first end configured for molding a part having an undercut, the undercut release component being movably engaged with the mold; and (ii) moving the undercut release component alternately between a first position wherein the first end aligns with the mold to form a continuous molding surface and a second position wherein the first end is disposed away from the undercut, wherein the first end traces a 3-axis. path when moving between the first position and the second position.